Designers and manufacturers of professional wood working tools, such as table saws, routers and shapers, are constantly looking for ways to improve the efficiency and safety of their products. One improvement which has been widely adopted is the use of "hold downs" which are spring loaded bars or blocks which provide downward pressure on a wood panel as it is being pushed or pulled past a saw blade, router or shaper. One example of such a hold down is illustrated and described in U.S. Pat. No. 4,063,612 to Richard Atkins. In the Atkins patent, a housing includes a pair of legs which straddle a rip fence and a spring biased hold down arm is attached to the housing and extends downward at an angle therefrom to engage a wood panel being cut by a table saw. The housing can be pushed along the rip fence to urge the wood panel into the saw blade while keeping the operator's fingers clear.
Another example of a hold down is illustrated and described in U.S. Pat. No. 4,026,173 to Livick. In the Livick patent, again, the hold down device is attached to and is movable along a rip fence so that an operator's hand are kept clear of the saw blade.
Hold downs are also known which attach to a shaper work table andiextend over the shaper blade to engage a wood panel being shaped. An example of such a hold down, which is offered on the assignee's machines, is illustrated in FIG. 1, labeled as "PRIOR ART". The hold down of FIG. 1 which is described in detail below, includes a U-shaped bar which fits over the shaper blade and which is spring biased downward by a coil spring to apply downward pressure against a wood panel being shaped. The working height of the hold down is adjustable via a crank arm to allow for different thicknesses of wood panels.
The rip fence mounted hold downs of Livick and Atkins are suitable for use with table saws equipped with rip fences, but not with shapers or routers, and not for sawing lumber of a width such that it will not fit within a rip fence. Assignee's prior art hold down design, as represented in FIG. 1, has worked satisfactorily as a hold down, but, particularly for wood panels of larger thicknesses, does not provide as effective of a barrier for minimizing the exposure of an operator to a working tool.
It is clear, then, that a need exists for an improved hold down device for use with wood working tools, such as table saws, routers and shapers. Such an improved hold down should provide downward pressure against a wood panel being shaped or cut and should allow an operator to feed the wood panel through the wood working tool while minimizing the exposure of the operator to the operating tool. Finally, such a hold down should be easily adjustable to accommodate different thicknesses of wood stock.